Roasting appliance

Abstract

An appliance for thermally processing granular material, especially for roasting food items such as coffee beans. The granular material lies on a perforated base through which gas flows upwardly to create a fluidized bed. The exhaust gas is fed to a cyclone separator for separation of entrained solid particles. Preferably, the base is located in an inner chamber which is at least partially enclosed in an outer chamber forming the cyclone separator. The exhaust gas is fed into a top opening of the outer chamber thereby providing a rotary gas flow. Alternatively, the base is located in an outer chamber in which at least the area above the base is designed as the cyclone separator. The outer chamber at least partially encloses an inner chamber through which gas is fed to create a rotary gas flow. In both cases, an extremely compact roaster design is realized.

What is claimed is:  
     
       1. In an appliance for roasting coffee beans, wherein the coffee beans to be roasted lies on a perforated base ( 31 ), a gas flows through the base from below creating a fluidized bed, and exhaust gas is fed from said fluidized bed to a cyclone separator for separation of entrained solid particles, the improvement comprising said base ( 31 ) being located in an outer chamber ( 32 ) in which at least an area above said base is designed as a cyclone separator, said outer chamber at least partially enclosing an inner chamber ( 33 ) through which the gas is fed from beneath said base into said outer chamber in a rotary flow ( 36 ). 
     
     
       2. An appliance according to  claim 1 , wherein a flow of gas in an upper part ( 35 ) of said inner chamber ( 33 ) connects to a flow of gas in said outer chamber ( 32 ) so that at least part of the gas circulates. 
     
     
       3. An appliance according to  claim 1 , wherein at least one of said outer chamber ( 32 ) and said inner chamber ( 33 ) has a substantially circular cross section. 
     
     
       4. An appliance according to  claim 3 , wherein said outer chamber ( 33 ) and said inner chamber ( 32 ) are substantially concentric to each other. 
     
     
       5. An appliance according to  claim 1 , further comprising a ventilator ( 34 ) which produces said rotary flow and which is located in a lower part of said inner chamber ( 33 ), wherein a suction side of said ventilator faces said inner chamber ( 33 ) while a pressurized side of said ventilator faces said outer chamber ( 32 ). 
     
     
       6. An appliance according to  claim 5 , wherein said ventilator ( 34 ) is a radial aerator having an aerator wheel which is coaxial to at least one of said inner and outer chambers. 
     
     
       7. An appliance according to  claim 1 , further comprising guide baffles ( 40 ) for reinforcing said rotary flow in the gas flow between a wall of said inner chamber and a wall of said outer chamber. 
     
     
       8. An appliance according to  claim 1 , further comprising at least one heating device for heating said rotary flow of gas and spaced from said fluidized bed. 
     
     
       9. An appliance according to  claim 8 , wherein said heating device includes at least one burner ( 42 ) with a flame tube ( 43 ,  44 ) which leads downwardly and into a top of said inner chamber ( 33 ). 
     
     
       10. An appliance according to  claim 9 , wherein said flame tube ( 44 ) has at least one opening ( 45 ) through which at least a partial flow of a return portion of said rotary flow of gas enters into said flame tube for afterburning. 
     
     
       11. An appliance according to  claim 1 , wherein said outer chamber ( 32 ) has at least one radially outward opening ( 37 ) for removing the separated solid particles. 
     
     
       12. An appliance according to  claim 1 , wherein said outer chamber ( 32 ) has a side wall with an outer opening ( 47 ) which is located at a level corresponding to said base and through which the coffee beans are removable. 
     
     
       13. An appliance according to  claim 1 , wherein said outer chamber has an outer wall ( 39 ) and wherein at least a portion of said outer wall is transparent.